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Hydroisomerization and hydrocracking of octylcyclohexane (C14H28) were performed over Pt and NiMoS‐supported catalysts, at 300 °C and 60 bar, with a molar H2 to hydrocarbon ratio of 7 mol/mol. The feed, composed of 5 wt.% phenyloctane dissolved in n‐heptane, was initially hydrogenated in situ over a pre‐catalyst, Pt or NiMoS/Al2O3. The C14 naphthene underwent isomerization and cracking under high hydrogen pressure over the bifunctional catalysts, whose acid function was represented by large‐pore zeolities (USY, Beta) or amorphous silica‐alumina (SA). For the Pt‐catalysts, Beta was slightly more active than USY. Both zeolites produced a similar product pattern. Sulfide catalysts were less well equilibrated than Pt ones and hence less active. They led to some over‐cracking, but the cracking selectivity of our naphthene reactant was much less sensitive to the metal‐acid balance than the cracking selectivity of n‐alkanes. The comparison of reactivity of octylcyclohexane with n‐hexadecane and perhydrophenanthrene is also discussed. [ABSTRACT FROM AUTHOR]

Environmental regulations concerning fuel‐related sulfur emissions are currently experiencing worldwide expansion. This is motivating the research and development of improved hydrotreating (HDT) catalysts with carefully engineered synthesis methods that maximize activity as ultimate goal. In this contribution, the effect of phosphorus doping and triethylene glycol (TEG) incorporation on the genesis of the CoMoS phase of model HDT catalysts is assessed. Following a surface‐science approach, α‐Al2O3 single crystals with four orientations: C(0001), A(112‾ 0), M(101‾ 0), and R(11‾ 02) are used as model supports of the traditional γ‐Al2O3 support for the study of active phase‐support interactions at the molecular scale. The model catalysts are prepared by traditional impregnation of a solution containing metal and phosphorus precursors and TEG. The catalysts are characterized in the sulfide phase by XPS, XAS, TEM, and AFM, revealing that the calcination step is key in the emergence of distinctive metal‐support interactions, which are directly related to the nature of alumina surface sorption sites. In addition, TEG incorporation on dried catalysts increases metal sulfidation and enhances promotion with respect to non‐additivated systems, especially at mild sulfidation temperatures. The catalytic activity of the model catalysts is tested in a thiophene hydrodesulfurization reaction, revealing the following activity trend with respect to alumina surface orientations: A112‾0 ≫ M101‾0 >R11‾02 , C(0001). This trend is identical to the one observed for non‐phosphorus doped non‐TEG additivated model systems, confirming the predominance of surface effects on the catalytic activity over those exerted by P and TEG. By transposing these results to the industrial γ‐Al2O3 support, the (100) facet would provide surface sites that lead to better performing catalysts. This could result in the development of novel supports, engineered to expose surface sites that maximize hydrotreating activity. [ABSTRACT FROM AUTHOR]

• An accelerated deactivation protocol at the pilot plant scale was developed to study hydrocracking catalyst deactivation in a short time of 30 days. • The organic nitrogen content of the feedstock to the hydrocracking process deactivates the catalyst acid function permanently by coke deposition. In contrast, nitrogen compounds have just an inhibitory effect on the metal function. The deactivation of the metal function is mainly due to nickel depromotion. • The balance in the ratio of the metal/acid sites determines the amount and the type of formed coke. The lower the ratio, the higher the coke production rate with a more aromatic structure. • Along the catalytic bed, the metal/acid balance decreases from bed inlet to bed outlet, the bed outlet contains a higher amount of coke, which is more aromatic. A representative accelerated experimental deactivation procedure was developed to understand the activity loss of bifunctional vacuum gasoil (VGO) hydrocracking catalysts over time. Experiments were performed in an up-flow fixed-bed pilot unit with a typical vacuum gas oil feedstock. The deactivation was measured by tracking the decrease of VGO conversion (370 °C+) with time on stream. The catalyst consisted of nickel-molybdenum sulfide particles dispersed on a carrier containing USY zeolite. The impact of temperature, liquid hourly space velocity (LHSV), hydrogen to hydrocarbon (H 2 /HC) ratio and organic nitrogen (N org) on the catalyst deactivation rate was first studied. The variables with the most significant impact on conversion loss were temperature and space velocity. Temperature directly influences the production rate of coke precursors, whereas space velocity affects the local concentration of feed contaminants along the reactor. Based on these results, the following operating conditions were selected to establish the final accelerated deactivation experimental protocol: T = 418 °C, LHSV = 3 h−1, H 2 /HC = 1500NL/L, P = 14 MPa, organic nitrogen content (Norg) = 150 ppm weight, total nitrogen content = 2500 ppm weight and a total time on stream of 30 days. Spent samples from this procedure presented similar properties to some industrial catalysts submitted to cycle lengths between 12 and 18 months. Both types of samples yield similar values of surface area and pore volume loss as well as a similar amount and nature of coke deposits. These results led to the qualitative validation of the protocol representativeness. This experimental procedure was then used to get more insight into the deactivation phenomenon. It was found that the organic nitrogen content of the feedstock is crucial, as it determines the ratio between available metal and acid sites. This ratio determines the reactions that take place and, therefore, the type of coke produced. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co promotion do not alter metal-support interactions compared to non-promoted systems. • Co promotion is not surface-dependent but contingent to the formation of MoS 2. • Highest catalytic activity for metal-support interactions of intermediate strength. The current environmental and industrial contexts require constant revision and improvement of hydrotreating processes for obtaining cleaner (bio)fuels through the development of supported transition metal sulfide (TMS) catalysts. The present work proposes a surface-science approach to describe the surface-dependent genesis of the cobalt-promoted active phase (CoMoS) supported on α-Al 2 O 3 single crystals used as surrogates of the industrial γ-Al 2 O 3 support. Co-Mo precursor solutions are deposited by aqueous-phase impregnation onto four α-Al 2 O 3 single crystals of C(0001), A (11 2 ¯ 0) , M (10 1 ¯ 0) , and R (1 1 ¯ 02) orientations, which display specific OH sorption sites. The model catalysts are characterized in the oxide and sulfide states by XPS, AFM, and TEM revealing a surface dependent sulfidation and dispersion as a result of metal-support interactions of diverse nature. The surfaces can be ranked following metal-support interactions of increasing strength C(0001) < A (11 2 ¯ 0) , M (10 1 ¯ 0) < R (1 1 ¯ 02) in good agreement with model non-promoted catalysts. However, AFM and TEM imaging also reveal that cobalt incorporation leads to an increase in the stacking of CoMoS particles with respect to non-promoted catalysts. The activity of the model catalysts in thiophene hydrodesulfurization cannot be simply related to the common features of the active phase (sulfidation, dispersion, promotion extent) but a volcano-shape curve is obtained when plotting the activity as a function of metal-support interactions. These results suggest that high activity is obtained on surfaces with intermediate metal-support interactions that lead to an optimal metal-sulfur bond energy in agreement with the Sabatier principle. Transposing these results to the traditional γ-Al 2 O 3 support suggests an enhanced activity of the (1 0 0) facet, which can lead to the development of improved supports for hydrotreating catalysts. [ABSTRACT FROM AUTHOR]

• VGO from conversion processes have a very different distribution of neutral nitrogen species than straight run VGOs. • Transition of neutral to basic N-species was observed for heavy coker gas oil. • DBE shift in basic nitrogen species depends on the number of the carbon atoms. • Neutral species with high DBE convert into carbazoles, which are "refractory". • Isomeric characterization is necessary for the selection of the reactivity descriptors. This paper is a part of a study on reactivity descriptors in vacuum gas oil hydrotreatment (VGO HDT). It aims to understand the differences in feeds of various process origins and the corresponding hydrotreated effluents on a molecular level. Four different vacuum gas oils were hydrotreated over a sulfided NiMo/Al 2 O 3 catalyst at a wide range of temperatures and residence times in order to collect HDT effluents at a broad range of hydrodenitrogenation (HDN) conversions. Vacuum gas oils and HDT effluents have been analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) in positive ESI(+) and negative ESI(-) electrospray ionization modes to characterize the basic and neutral nitrogen-containing species and the subtleties of HDT transformations depending on the feedstock type. [ABSTRACT FROM AUTHOR]